The thing about housing or small business electrical power is the voltage from the electrical power source such as an Utility Company is a very high voltage. There are two things in regard to a very high voltage is there will be less energy loss due to the resistance of the electrical transport wiring to typically a pole mounted transformer.

The primary reason the transformer is on a pole is to keep individuals away from the input wiring because as an example 30,000 volts is typically used in ignition systems for gasoline engines to supply electrical voltage to a Spark Plug. In other words, 30,000 volts will leap across a 1/16" gap between the wire and the electrical return which typically is the case of the engine.

So in other words if a human got too close to the higher voltage input to the transformer it is possible a spark could be created and strike the human and due to the voltage level like kill the human.

On the other side of the transformer coin is 240 volts will not likely jump to and strike a human and yet 240 volts is more than enough to power things like Electric Stoves, Electric Hot Water Heaters, Clothes Dryers, & Air Conditioners. Where the 120 volts is more than enough for standard in home utility items such as a Hair Dryer, Coffee Pot, Vacuum & Computer.

The reason the house voltage is AC "Alternating Current" because to enable the electrical energy to transport from one wiring coil in a transformer to another coil is the Electrical Energy needs to change in amplitude and polarity In other words the AC is 60 Changes " Cycles" per second or .01666667 second the polarity is A=+ & B=- for .008333333 Second and the B=+ and A=- for .008333333 second or 1.2 of 1/60th of a second and then the cycle effort starts over again for a total of 60.

SINE WAVE EXAMPLE TIME BETWEEN A&A 1/60th Second

What is shown below is a typical wiring connection from a POWER Company to a transformer mounted on a pole. Though not always the same the transformer input voltages around 10,000 volts. Also in many case the input wiring is QTY of three but the drawing only shows two representing one customer.

The transformer output is three wires. The voltage between the outer wires is 240 and between one outer wire and the center wire is 120 meaning there is 2 120 volt supply circuits from the pole transformer to the Service Panel via the Meter used for power usage measurement.

Additional pictures shown down the page are lesser complex with intent if focusing on a specific topic. The KEY THING to REMEBER is the voltage are to be transported from the service panel to electrical items such as lighting,receptacles, heating fans, Ceiling Fans by using One of Three colors {Black, RED, or Blue} A typical example of 240 volt circuit in general is the use of two Black wires but they could be Black & Red or Black & Blue or Red & Blue. In general most 3 wire cables are Black, Red, & White which is the neutral. Also there is a bare copper wire to be used for Ground or in used in an item like Conduit the Ground Wire can be Green.

The Picture above shows the electical contact between wires based on which part of the switch is pushed. Push Top Light ON & bottom Light Off and wires not conncted due to internal switch component

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The Primary Objective of the picture above is to show the wiring from the Service Panel to what is called a Single Pole Single Throw Switch and then to a Light Bulb Socket. The Socket wiring example shows the black AKA Hot or Switched 120 Volt AC Wire which is connected to the screw on the Porcelain Socket that delivers to the Center Contact on a Light Bulb. The White Wire goes to the screw that delivers to the outer bulb or screw type contact. Not shown is a Brass Wire that goes from the Ground COntact Point in the Service Panel to the Ground Screw on the Porcelain Socket.

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